1. Field of the Invention
This invention relates to apparatus for testing flat panel display, and particularly relates to apparatus for testing liquid crystal display (LCD).
2. Description of the Prior Art
As the trend of shrinking volume of electrical device and reducing radiation produced by the display device, the cathode ray tube (CRT) display is gradually replaced with the flat panel display. But the technology for fabricating the flat panel display device results in the high cost of the flat panel display device, which confines the use of flat panel display device. After a long term of developing the fabricating technology for manufacturing flat panel display device, such as LCD, the yield of fabricating LCD is raised, and the technology is getting mature day by day. In recent years, application of flat panel display devices to word processors, lap-top personal computers, pocket size TV display, and the like have been rapid progress. Especially, the liquid crystal display (LCD) is widely used in every kinds of application due to the maturity of process that fabricating the LCD panel.
In early years, because LCD is very expensive, and the technology is immature, the application of LCD is only in a narrow field, thus only few sizes of LCD is utilized in few applications. As the fabrication technology progressed, the yield of fabricating LCD is raised, and cost is down gradually. So the application of LCD is getting more wide, and the size of LCD is getting larger. To replace the CRT display, the enlargement of the area of the LCD panel is necessary, so the technology used to fabricate the large size LCD panel is developed. Though the large size LCD is getting more popular, the application of small size LCD is unavoidable.
Because the LCD panel is composed of many LCD cells and other devices, in addition, the larger LCD panel has more devices. Even a single device in the LCD panel is out of order, the whole LCD panel is thus fail. So the test for the fabricated LCD panel is a very important step to ensure the quality of the fabricated LCD panel before packaging. To verify whether the fabricated LCD panel can work properly, the probe card is utilized to test the fabricated LCD panel. In earlier years, only few kinds of LCD sizes are utilized in application, so only few kinds of sizes of probe card are utilized to test the LCD panel. Though only few kinds of sizes of probe card are utilized, and each size of probe card is designed for a specific LCD size, because few sizes of LCD panel are utilized, so that few sizes of probe card are enough.
Due to various applications of LCD panel, the LCD panel of various sizes are developed, and the probe card of corresponding sizes are designed and fabricated to test the LCD panel of corresponding size. Whereas in the LCD panel factory, one test station can only test LCD panels of one specific size. If the size of the produced LCD panel is to be changed, the probe card must be replaced to fit the new size of the produced LCD panel. To illustrate the operation of the prior art probe card utilized to test the flat panel display, such as LCD panel, the configuration of the prior art LCD panel testing device is illustrated in FIG. 1a, in which the probe card is utilized. As shown in FIG. 1a, the LCD panel testing device includes the pattern generator 10, the control board 13, the scan circuit board 15, the data circuit board 17, and the probe card 19. Besides the LCD panel that is to be tested is LCD panel 25. When testing the LCD panel 25, the pattern generator 10 generates the pattern that is to be shown in the display panel (LCD panel 25). The control board 13 feeds a data line driving signal ds to the data circuit board 17 and feeds a scan line driving signal ss to the scan circuit board 15 respectively according to the output signal of the pattern generator 10. The scan circuit board 15 feeds the scan line driving pulse sp to the probe card 19 responding to the scan line driving signal ss, and feeds the data line driving pulse dp to the probe card 19 responding to the data line driving signal ds.
To further illustrate the operation of testing the LCD panel, the amplified view of the area in the dashed circle D in FIG. 1a is shown in FIG. 1b. In which a plurality of probe pin 27 is electrically coupled to the edge of probe card respectively, and the other terminal of each of the plurality of probe pin 27 is also electrically coupled to the pad 30 of the LCD panel 25 by physical touching. So the devices in the LCD panel can be tested by the LCD panel testing device through the probe card 19. For the description mentioned above, the number of pin 27 of the probe card 19 is fixed and the size of the probe card 19 is fixed. If a new LCD panel has a larger size than that of the original LCD panel, it is impossible to use the original probe card to test the LCD panel of a larger size. Also, if the size of the fabricated LCD panel of the production line is to be changed. In other words, when the production line is used to fabricate the LCD panel of the other size, then the probe card on the production line must be changed to a specific size that fits for the of the other size of LCD panel. It takes about 1-2 hours to change the probe card of the production line, and it's a long time wasted in fabricating LCD panel.
In addition, in developing a specific LCD panel, it is necessary to test the fabricated specific LCD panel, so the purchase of the probe card of corresponding specification is necessary. Whereas each probe card costs about 10,000 US dollars, its very expensive, and if the developed specific LCD panel is not to be mass produced, the probe card of corresponding specification will become useless, thus the waste of investment is resulted. Furthermore, as the technology advances getting more quickly, LCD of one specification will probably be replaced with LCD of another specification within the lifetime of the ordinary probe card. So the replacement of a new probe card is necessary, and the ordinary probe card become useless.
Besides, it takes about two months for the probe card maker from getting an order for purchasing a probe card to realizing the designed probe card. If the foregoing duration can be saved, it makes benefit in developing the LCD of a new specification. In other words, the duration of developing a LCD panel of a new specification is reduced. According to the disadvantages mentioned above, the prior art probe card needs improvement.